Have you ever wondered how someone who can't see can clean up their seeing eye dog's mess? Mental Floss has a great article that answers this burning question:

Dogs go into different stances depending on whether they’re peeing or pooping, and by running a hand down the dog’s back, the handler can figure out what’s going on. If the dog’s back is flat, it’s peeing — male guide dogs are trained to not lift their leg when peeing; they utilize the same “lean forward” pee stances that females use — and no cleanup if needed. If the dog’s back is rounded, handlers know some cleanup will be required. By feeling their way down the dog’s back to its butt and tail, they have a pretty good idea of where the poop is going to wind up. Once the dog is finished, the handler just leans down with their plastic bag and can find the poop pretty easily.

I question how easy it is to find the poop by feeling around with your hand inside a plastic bag. Sorry to get gross here, but sometimes the poop is really soft and you wouldn't even know you were touching it, through a plastic bag.

blind guy stands at a bus stop with his service dog. dog sniffs guy's leg, lifts his & begins to pee on his owner's leg. guy reaches down & pats dog on head. woman standing nearby, watching, says " your dog just peed on your leg & you pet him? blind guy says "I'm trying to find his head so I can kick his a**.